Ketonitriles and method for their production

ABSTRACT

Ketonitriles of the general formula   IN WHICH R1 and R2 signify alkyl groups with one to four carbonatoms, R3 and R4 are hydrogen atoms or alkyl groups with one to four C-atoms and wherein R3 and R4 may also together form a carbocyclic ring preferably with five or six C-atoms and n is zero, 1 or 2 produced by condensing diols of the formula   WITH CYANALDEHYDES OF THE FORMULA WHEREIN R1, R2, R3, R4 and n have the same meanings as set forth above, in the presence of strong acid catalysts where the diols may be in the thickly liquid, impure form. These ketonitriles are useful as herbicides.

nited States Patent [191 Blumenfeld et al.

[54] KETONITRILES AND METHOD FOR THEIR PRODUCTION [75] Inventors: GeorgBlumenfeld, Troisdorf-Siegler; Gerhard Daum, Cologne-Rad erberg; HermannRichtzenhain,

' Schwellbach, all of Germany [73] Assignee: Dynamit Nobel AG,Troisdorf, Germany 22 Filed: Jan. 28, 1970 21 App]. No; 6,575

[30] Foreign Application Priority Data Primary ExaminerAlex MazelAssistant ExaminerJames H. Turnipseed Attorney-Burgess, Dinklage &Sprung [57] ABSTRACT Ketonitriles of the general formula [4 1 Mar. 27,1973 in which R and R signify alkyl groups with one to fourcarbon-atoms, R and R are hydrogen atoms or alkyl groups with one tofour C-atoms and wherein R and R may also together form a carbocyclicring preferably with five or six C-atoms and n is zero, 1 or 2 producedby condensing diols of the formula I CH:OH CHr-OH with cyanaldehydes ofthe formula i R3 HC-C(CH1)nCN wherein R R R R and n have the samemeanings as set forth above, in the presence of strong acid catalystswhere the diols may be in the thickly liquid, impure form. Theseketonitriles are useful as herbicides.

3 Claims, No Drawings KETONITRILES AND METHOD FOR THEIR PRODUCTION Thisinvention relates to ketonitriles. It more particularly refers tospecial novel ketonitriles and to the production thereof.

One aspect of this invention are ketonitriles of the formula wherein Rand R may be the same or different and are each alkyl groups of up tofour carbon atoms in straight or branched chain configuration; R and Rmay be the same or different and are each hydrogen or alkyl of up tofour carbon atoms which may form a carbocyclic ring together with thecarbon atom to which they are attached of about five or six ring carbonatoms which ring may have one or more, up to about four lower alkylsubstituents of up to about 4 carbon atoms each; and n is a whole numberof zero to 2.

Of special note is the ketonitrile of the above structural generalformula where R,, R R and R are each methyl and ri is 2. This compoundhas the structural formula Another special ketonitrile of this inventionis the compound where R and R are methyl, R is ethyl, R is n-butyl, andn is 2. This compound has the structural formula CHPO cm-cm-cm-cmAnother aspect of this invention is in the production of theseketonitriles which takes place by condensation of diols of the generalformula CHIOH with cyanaldehydes of the general formula permeated withcrystals, can be achieved only by multiple recrystallizations.

It has therefore been surprisingly found that it is possible to carryout the condensation reaction of this invention using these impurematerials which are only to a slight degree crystallized to obtain theketonitriles of this invention in good yields and adequate purity.

Suitable cyanaldehydes are, for example, cyanoacetaldehyde,3cya.nopropionaldehyde, 4- cyanobutyraldehyde,2,2-dimethyl-4-cyanobutyraldehyde, 2,2-diethyl-4-cyanobutyraldehyde,2-ethyl-2- isopropylA-cyanobutyraldehyde, 2-ethyl-2-n-butyl-4-cyanobutyraldehyde, l-(B-cyanoethyl) -cyclo hexeneand1-(Bcyanoethyl)-cyclohexyl-alin the presence of strongly acid catalysts,such as, for

example, phenyl-sulfonic acid, benzenesulfonic acid, toluenesulfonicacid or hydrogen chloride, and the formed water is azeotropicallyremoved from the reaction mixture.

The products in accordance with the invention are present asisomer-mixtures dues to the possible axial or equatorial arrangement ofthe substituents of C and C with respect to the 1,3-dioxane ring.

It was possible to separate the ketonitrile so produced by condensationfrom the cyanaldehyde and diol reactants (e.g., 2-methyl-2-acetyl-l,3-propandiol with 2,2-dirnethyl-4-cyano-butyraldehyde'), for example,by fractionating and/or crystallization. From these particularillustrated reactants a compound melting at 6768 C, which represents oneof the possible isomers, can be separated from the reaction mixturewhich melts about l0-l 5 C lower.

The reaction temperature is not critical and is dependent, when using anazeotroping agent for the removal of water, on the boiling point of theazeotrope or of the water. The reaction can take place at temperaturesas low as below C. It is preferred that the azeotroping agents and theinert solvents are the same material, preferably with boiling pointswhich are in the range of about 80l 60C.

The ketonitriles in accordance with the invention are valuableherbicides and also are intermediate products for the construction ofother compounds, such as keto acids, by hydrolysis of the nitrile group.

The following examples serve to illustrate this invention without beinglimiting thereon:

EXAMPLE 1 One hundred thirty-two g of 2,2-dimethylolbutanone-(3), 125 gof 2,2-dimethyl-4-cyanobutyraldehyde, 200 ml xylene and 2 gp-toluene-sulfonic acid were heated together in a l-liter two-neck-flaskwhich was provided with a water separator, a reflux condenser, and amagnetic stirrer, to such an extent that it was possible to azeotropeoff the reaction water with the boiling xylene solvent. The bathtemperature was maintained at about l65-l70C. After 60 and minutes,respectively, the condensation reaction was again accelerated by theaddition of 2 g each time of ptoluene-sulfonic acid. After 180 minutes,18 ml water had separated, thus signifying completion of the reactionwhich was then terminated.

Most of the xylene was distilled off and the remaining precipitate wasfiltered with suction. The filtrate was mixed with 200 ml toluene, wellwashed with weight percent K Co -aqueous solution and afterwards withsaturated NaCl-solution, and the organic layer was dried over K CO Afterfiltrating off from K CO the solvent was separated via a 40cm-Vigreux-column and the remainder of 210 g of product distilled invacuum.

After a first running of g, there was obtained at (B?) 0.1 l35147C acolorless liquid which solidified as it came off in the first running.It had an indistinct melting point between 40 and 45 C.

Yield 177.5 g 74% of 2-[(l,l-dimethyl-3-cyano)- propyl]-5-methyl-5-acetyldioxane-( l ,3). The compound is present as isomermixture.

The isomeric mixture may be separated by fractionated crystallizationfrom petroleum ether having a boiling point of 40-60C. A pure isomer,which is clearly distinguishable by its crystal form (flat triangles)and its melting point (67-68C), from the remainder of the mixture(needles having an indistinct melting point which may vary from about 50to about 59C) can thus be recovered.

Ninety five g 2,2-dimethylolbutanone-(3), 130 g 2-ethyl-2-n-butyl-4-cyanbutyraldehyde, 400 ml benzene and 2,5 gp-toluene-sulfonic acid were heated together in a l-liter two-neck-flaskwhich was provided with a water separator, a reflux condenser, and amagnetic stirrer. At a bath temperature of about 120C, the reactionwater was carried off with the boiling benzene. After 150 minutes, thecalculated stoichiometric amount of condensed water 13 ml) hadseparated.

The benzene was distilled off to a large extent, the turbid reactionmixture was hot filtered, and the filtrate was freed, in the water jetvacuum, from the remaining solvent and then distilled. After a firstrunning of 49 g which contained partly unconverted starting material,there was obtained at (Bp) l50-l70C 136 g of 2- l-ethylln-butyl-3-cyano)-propyl]-5 methyl-5- acetyl-dioxane-( 1.3) 64 percent oftheory as a colorless oily liquid. In the purification by redistillationthe main fraction passed overhead at boiling point 152C n 1.4716. Theisomer mixture was not resolved.

wherein R and R each is an alkyl of one to four C- atoms R, and R arehydrogen or an alkyl of one to four C-atoms provided that R and Rtogether with the carbon atom to which they are attached, may also be acarbocyclic ring of five to six C-atoms, and n is zero to 2.

2. A ketonitrile as claimed in claim 1 wherein R R R and R are eachmethyl, and n is 2, having the structural formula:

3. A ketonitrile as claimed in claim 1 wherein R and R are each methyl,R is ethyl, R is n-butyl, and n is 2, having the structural formula:

2. A ketonitrile as claimed in claim 1 wherein R1, R2, R3, and R4 areeach methyl, and n is 2, having the structural formula:
 3. A ketonitrileas claimed in claim 1 wherein R1 and R2 are each methyl, R3 is ethyl, R4is n-butyl, and n is 2, having the structural formula: